Isuzu Trooper (1998-2002 year). Manual - part 607

6E–76

4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS

DTC P0123 – AP Sensor High Voltage

 

Step

Action

Value(s)

Yes

No

1

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go to 

Step 2

Go to 

OBD

System

Check

2

Check the AP sensor signal circuit.

Was the AP sensor signal circuit open or darmage?

—

Replace the

APS circuit

Go to 

Step 3

3

1. Ignition “ON,” engine “OFF.”
2. With the throttle closed, observe the “AP Sensor”

display on the Tech 2.

Is the “AP Sensor” above the specified value?

4.5 V

Go to 

Step 5

Go to 

Step 4

4

1. Ignition “ON,” engine “OFF.”
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records

conditions as noted.

4. Using a Tech 2, monitor “DTC” info for DTC P0123.

Does the Tech 2 indicate DTC P0123 failed.

—

Go to 

Step 5

Refer to

Diagnostic

Aids

5

1. Disconnect the AP sensor electrical connector.
2. Observe the “AP Sensor” display on the Tech 2.

Is the “AP Sensor” near the specified value?

0 V

Go to 

Step 6

Go to 

Step 7

6

Probe the sensor ground circuit at the AP sensor
harness connector with a test light connected to B+.

Is the test light “ON?”

—

Go to 

Step 8

Go to 

Step 11

7

1. Ignition “OFF,” disconnect the ECM.
2. Ignition “ON,” engine “OFF.”
3. Check for a short to voltage on the AP sensor signal

circuit.

4. If the AP sensor signal circuit is shorted, repair it as

necessary.

Was the AP sensor signal circuit shorted?

—

Verify repair

Go to 

Step 13

8

1. Ignition “ON.”
2. Monitor the “AP Sensor” Tech 2 display while

disconnecting each of the components that share
the 5 volt reference “J2” circuit (one at a time).

3. If the “AP Sensor” Tech 2 display changes, replace

the component that caused the display to change
when disconnected.

Does disconnecting any of these components cause
the “AP Sensor” display to change?

—

Verify repair

Go to 

Step 9

9

1. Ignition “OFF,” disconnect the ECM.
2. Ignition “ON,” engine “OFF.”
3. Check for a short to B+ on the 5 volt reference “A”

circuit.

4. If the 5 volt reference “J2” circuit is shorted, repair it

as necessary.

Was the 5 volt reference “J2” circuit shorted?

—

Verify repair

Go to 

Step 10

10

Check for poor electrical connections at the AP sensor
and replace terminals if necessary.

Did any terminals require replacement?

—

Verify repair

Go to 

Step 12

6E–77

4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS

DTC P0123 – AP Sensor High Voltage

  (Cont'd)

Step

No

Yes

Value(s)

Action

11

1. Ignition “OFF.”
2. Disconnect the ECM, and check for an open sensor

ground circuit to the AP sensor.

3. If a problem is found, repair it as necessary.

Was the sensor ground circuit to the AP sensor open?

—

Verify repair

Go to 

Step 13

12

Replace the AP sensor.

Is the action complete?

—

Verify repair

—

13

Replace the ECM (Refer to the Data Programming in
Case of ECM change).

Is the action complete?

—

Verify repair

—

6E–78

4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P0182 (Flash DTC 15) 

FT Sensor Low Voltage

060RW129

Circuit Description

The fuel temperature (FT) sensor is a thermistor mounted
on a coolant crossover pipe at the rear of the engine.  The
Engine Control Module ECM applies a voltage (about 5
volts) through a pull-up resistor to the FT signal circuit.
When the fuel is cold, the sensor (thermistor) resistance
is high, therefore the ECM will measure a high signal
voltage.  As the fuel warms, the sensor resistance
becomes lower, and the FT signal voltage measured at
the ECM drops.

Action Taken When the DTC Sets

D

The ECM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.

Conditions for Clearing the MIL/DTC

D

DTC P0182 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the ECM battery
feed.

Diagnostic Aids

Check for the following conditions:

D

Poor connection at ECM – Inspect harness connectors
for backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal-to-wire connection.

D

Damaged harness – Inspect the wiring harness for
damage.  If the harness appears to be OK, observe the
FT display on the Tech 2 while moving connectors and
wiring harnesses related to the FT sensor.  A change
in the FT display will indicate the location of the fault.

If DTC P0182 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.
If it is determined that the DTC occurs intermittently.

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Verifies that the fault is present.

6E–79

4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS

DTC P0182 – FT Sensor  Low Voltage

 

Step

Action

Value(s)

Yes

No

1

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go to 

Step 2

Go to 

OBD

System

Check

2

1. Ignition “ON,” engine “OFF.”
2. Observe the “Fuel Temp” display on the Tech 2.

Is the “Fuel Temp” below the specified value?

139

°

C

(282

°

F)

Go to 

Step 4

Go to 

Step 3

3

1. Ignition “ON,” engine “OFF.”
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records

conditions as noted.

4. Using a Tech 2, monitor “ DTC” info for DTC P0182.

Does the Tech 2 indicate DTC P0182 failed this
ignition?

—

Go to 

Step 4

Refer to

Diagnostic

Aids

4

1. Disconnect the FT sensor electrical connector.
2. Observe the “Fuel Temp” display on the Tech 2.

Is the “Fuel Temp” at the specified value?

–39

°

C

(–38

°

F)

Go to 

Step 6

Go to 

Step 5

5

1. Ignition “OFF.”
2. Disconnect the ECM and check the FT signal circuit

for a short to ground or a short to the sensor ground
circuit.

3. If the FT signal circuit is shorted. repair it as

necessary.

Was the FT signal circuit shorted to ground?

—

Verify repair

Go to 

Step 7

6

Replace the FT sensor.

Is the action complete?

—

Verify repair

—

7

Replace the ECM (Refer to the Data Programming in
Case of ECM change).

Is the action complete?

—

Verify repair

—